Technical Brief

Development of an Adjustable Sinus Tarsi Device for Flatfoot Correction: A Pilot Study in a Sawbones Model1

[+] Author and Article Information
Robert Rizza

Department of Mechanical Engineering,
Milwaukee School of Engineering,
Milwaukee, WI 53202

XueCheng Liu, Scott Van Valin, Roger Lyon

Department of Orthopaedic Surgery,
Medical College of Wisconsin,
Milwaukee, WI 53202

Accepted and presented at the Design of Medical Devices Conference (DMD2014), Minneapolis, MN, April 7–10, 2014.

Accepted and presented at The Design of Medical Devices Conference (DMD2014), April 7–10, 2014, Minneapolis, MN, USA.

Manuscript received February 21, 2014; final manuscript received March 3, 2014; published online April 28, 2014. Editor: Arthur G. Erdman.

J. Med. Devices 8(2), 020937 (Apr 28, 2014) (2 pages) Paper No: MED-14-1028; doi: 10.1115/1.4026999 History: Received February 21, 2014; Revised March 03, 2014

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RaoU. B., and Joseph, B., 1992, “The Influence of Footwear on the Prevalence of Flat Foot. A Survey of 2300 Children,” J Bone Joint Surg. Br., 74(4), pp. 525–527.
Smith, S., and Millar, E., 1983, “Arthrorisis by Means of a Subtalar Polyethylene Peg Implant for Correction of Hindfoot Pronation in Children,” Clin. Orthop., 181, pp. 18–23.
Needleman, R. L., 2006, “A Surgical Approach for Flexible Flatfeet in Adults Including a Subtalar Arthroereisis With the MBA Sinus Tarsi Implant,” Foot Ankle Int., 27(1), pp. 9–18.
Needleman, R. L., 2005, “Current Topic Review: Subtalar Arthroereisis for the Correction of Flexible Flatfoot,” Foot Ankle Int., 26(4), pp. 336–346.
Kitaoka, H., Luo, Z.-P., and Kai-Nan, A., 1998, “Reconstruction Operations for Acquired Flatfoot: Biomechanical Evaluation,” Foot Ankle Intl., 19(4), pp. 203–207. [CrossRef]


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Fig. 1

(a) CAD model with unexpanded wedges (1, 2, 3—main body, 4—expansion wedges, and 5—adjustment screw) and (b) model with wedges expanded

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Fig. 2

Sawbones® model of the flatfoot in the custom load frame

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Fig. 3

Comparison of the joint angle with expansion of the device to a baseline position of the foot (mean + SD)

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Fig. 4

Plantar pressure distribution (unexpanded device). Also shown are the COP trajectories for the foot with no implant and for a normal foot. A standard plantar pressure grid is used.



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